The present invention relates generally to connecting mechanism in a loom between the pick arm which extends from the pick shaft and the lug strap mounted on the picker stick. The invention relates more specifically to a novel lug strap connector.
In conventional looms, the shuttle is propelled across the width of the loom alternately from one side of the loom to the other by means of a picker stick at each side of the loom. Each picker stick is pivoted near the bottom of the loom and has two pivoting motions. The first motion is a swinging motion toward the opposite side of the loom for propelling the shuttle through the warp shed. The second motion is a swinging motion backwardly and forwardly of the loom as it moves with the backwardly and forwardly reciprocating lay. The mechanism for imparting the shuttle-sticking motion or picking motion to the picker stick does not move with the lay and receives its driving power from the loom drive mechanism in synchronization with other loom motions. The picker-driving mechanism comprises a horizontal pick shaft which includes a horizontally-extending portion (commonly referred to as a "picking shoe") which is struck by a picking roll rotating on the bottom shaft of the loom. The picking shoe itself may be in the form of a flat cam-like surface or a conical surface. Regardless of the picking drive used, the pick shaft is given a sharp, abrupt oscillation at the time of picking. A pick arm extends from the pick shaft and is operatively connected to the picker stick through a connecting mechanism which includes the lug strap connector extending between the lug strap and the pick arm. The longitudinal axis of the pick shaft extends from front to rear of the loom, so that the pick arm oscillates or swings in a plane which is parallel to the front of the loom. The picker stick also swings in this plane and also in a second plane which is parallel to the sides of the loom and is at a right angle to the first plane. The lug strap connector is rigidly clamped to the lug strap and is pivotally connected to the pick arm. This means that there is relative displacement between the pick arm and lug strap connector from their common pivoting point in the first plane when the picker stick is moved for a shuttle-picking operation. There is also relative displacement between the lug strap connector and the pick arm as the picker stick moves backwardly and forwardly during its motion with the lay in the second plane.
The composite differential displacement between the picker stick and pick arm is provided for in present loom designs in part by the looseness of the lug strap and a universal connection between the lug strap connector and the pick arm. A typical universal connection is in the form of a ball joint. Connections of this type are costly, require frequent lubrication, and tend to wear, thereby producing irregularities in picking. The added mass of the ball joint connection also creates additional stress and wear in existing checking or motion dampening mechanism associated with picking. In some looms the differential motion has been taken care of by using loose or large tolerance connections to the pick arm. This causes force or power losses during picking and also results in irregular picking. These and other difficulties experienced by the prior art devices have been obviated in a novel manner by the present invention.
It is, therefore, an outstanding object of the invention to provide a lug strap connector which provides consistent shuttle picking.
Another object of this invention is the provision of a lug strap connector which requires a minimum of maintenance.
A further object of the present invention is the provision of a lug strap connector which is inexpensive, simple to manufacture, and easy to assemble.
It is another object of the instant invention to provide a lug strap connector which is long lasting and reliable.
A still further object of the invention is the provision of a lug strap connector which has a smaller mass than that of conventional connectors, thereby creating less stress on the checking mechanism.
With these and other objects in view, as will be apparent to those skilled in the art, the invention resides in the combination of parts set forth in the specification and covered by the claims appended hereto.